Recent trends in the climate lead to predictions of significant change in both precipitation and temperature for the Midwestern states of the United States. These changes in our climate are bound to bring about changes in the functioning of all ecosystems. Due to its rarity at a global scale, the prairie ecosystem poses a particular concern in this situation. Our ability to look at this problem from a landscape level has been greatly enhanced for the recent developments in remote sensing technologies.
Geographic information system files were obtained from local state and nongovernmental agencies for the prairies in their region. These files were screened to ensure that the prairies met both size and vegetation requirements. The prairie outlines were then overlaid on six years of MODIS imagery in eight-day composites as to extract each prairies NDVI value. Date of green up, senescence date, peak green date and length of growing season were then obtained from each prairies NDVI curve. These phenological characters were then compared against precipitation and temperature patterns for the last six years.
Results/Conclusions
The preliminary results of this experiment show that prairie senescent dates become earlier in the year as yearly maximum temperatures increase (r2 = 0.3606). Trends also indicated that a negative relationship existed between precipitation and the length of the growing season (r2 = 0.2322). Predicted increases in precipitation of 25% and increases in temperatures of nearly 2oC for Midwestern states might mean significant changes to nutrient cycling as well as other ecosystem functions in the near future.
